1 files changed, 196 insertions, 0 deletions

diff --git a/src/renderer.rs b/src/renderer.rs
new file mode 100644
index 0000000..0792537
--- /dev/null
+++ b/src/renderer.rs
@@ -0,0 +1,196 @@
+use crate::game::Game;
+use crate::texture::TEX_SIZE;
+
+pub struct Renderer {
+    screen_w: usize,
+    screen_h: usize,
+    /// Precomputed: floor_dist_lut[row] = perpendicular distance to floor at that row.
+    floor_dist_lut: Vec<f64>,
+    /// Precomputed: floor_bright_lut[row] = brightness × 256 for that row (fixed-point).
+    floor_bright_lut: Vec<u32>,
+}
+
+impl Renderer {
+    pub fn new(screen_w: usize, screen_h: usize) -> Self {
+        let half_h = screen_h as f64 / 2.0;
+        let mut floor_dist_lut = vec![0.0f64; screen_h];
+        let mut floor_bright_lut = vec![0u32; screen_h];
+
+        // Only rows below the horizon have meaningful floor values.
+        for py in (screen_h / 2 + 1)..screen_h {
+            let dy = py as f64 - half_h;
+            let dist = 0.5 * screen_h as f64 / dy;
+            floor_dist_lut[py] = dist;
+            let bright = (1.0 / (1.0 + dist * 0.15)).max(0.05);
+            floor_bright_lut[py] = (bright * 256.0) as u32;
+        }
+
+        Self {
+            screen_w,
+            screen_h,
+            floor_dist_lut,
+            floor_bright_lut,
+        }
+    }
+
+    /// Produce one frame into `buffer` (packed `0xAARRGGBB`).
+    pub fn render(&self, game: &Game, buffer: &mut [u32]) {
+        buffer.fill(0xFF00_0000); // pure-black ceiling
+
+        let half_h = self.screen_h as f64 / 2.0;
+        let fov = std::f64::consts::PI / 3.0; // 60°
+
+        for sx in 0..self.screen_w {
+            let cam_x = 2.0 * sx as f64 / self.screen_w as f64 - 1.0;
+            let ray_angle = game.player.angle + (fov / 2.0) * cam_x;
+            let rdx = ray_angle.cos();
+            let rdy = ray_angle.sin();
+
+            // ---- DDA setup -------------------------------------------------
+            let mut map_x = game.player.x as isize;
+            let mut map_y = game.player.y as isize;
+
+            let ddx = if rdx == 0.0 {
+                f64::MAX
+            } else {
+                (1.0 / rdx).abs()
+            };
+            let ddy = if rdy == 0.0 {
+                f64::MAX
+            } else {
+                (1.0 / rdy).abs()
+            };
+
+            let (step_x, mut side_x) = if rdx < 0.0 {
+                (-1isize, (game.player.x - map_x as f64) * ddx)
+            } else {
+                (1isize, (map_x as f64 + 1.0 - game.player.x) * ddx)
+            };
+
+            let (step_y, mut side_y) = if rdy < 0.0 {
+                (-1isize, (game.player.y - map_y as f64) * ddy)
+            } else {
+                (1isize, (map_y as f64 + 1.0 - game.player.y) * ddy)
+            };
+
+            let mut hit_side: bool;
+            let euclidean: f64;
+
+            // ---- DDA loop --------------------------------------------------
+            loop {
+                if side_x < side_y {
+                    side_x += ddx;
+                    map_x += step_x;
+                    hit_side = false;
+                } else {
+                    side_y += ddy;
+                    map_y += step_y;
+                    hit_side = true;
+                }
+
+                if map_y < 0
+                    || map_y >= game.maze.height() as isize
+                    || map_x < 0
+                    || map_x >= game.maze.width() as isize
+                {
+                    euclidean = 1.0;
+                    break;
+                }
+
+                if game.maze.is_wall(map_y as usize, map_x as usize) {
+                    euclidean = if !hit_side {
+                        (map_x as f64 - game.player.x + (1.0 - step_x as f64) / 2.0) / rdx
+                    } else {
+                        (map_y as f64 - game.player.y + (1.0 - step_y as f64) / 2.0) / rdy
+                    };
+                    break;
+                }
+            }
+
+            // Fisheye correction
+            let perp_dist = (euclidean * (ray_angle - game.player.angle).cos().abs()).max(0.001);
+
+            // ---- wall slice ------------------------------------------------
+            let wall_h = (self.screen_h as f64 / perp_dist) as isize;
+            let draw_start = ((-wall_h / 2) + self.screen_h as isize / 2).max(0) as usize;
+            let draw_end = ((wall_h / 2) + self.screen_h as isize / 2)
+                .min(self.screen_h as isize - 1) as usize;
+
+            // Texture x-coordinate (uses Euclidean, not perp)
+            let wall_x = if !hit_side {
+                game.player.y + euclidean * rdy
+            } else {
+                game.player.x + euclidean * rdx
+            };
+            let wall_x = wall_x - wall_x.floor();
+            let tex_x = ((wall_x * TEX_SIZE as f64) as usize).min(TEX_SIZE - 1);
+
+            // Hoist: brightness is identical for every pixel in this column
+            let wall_bright_fx = {
+                let b = (1.0 / (1.0 + perp_dist * 0.12)).max(0.08);
+                (b * 256.0) as u32
+            };
+
+            for py in draw_start..=draw_end {
+                let tex_y = ((py as f64 - half_h + wall_h as f64 / 2.0) * TEX_SIZE as f64
+                    / wall_h as f64) as usize;
+                let tex_y = tex_y.min(TEX_SIZE - 1);
+
+                let color = game.wall_texture[tex_y * TEX_SIZE + tex_x];
+                buffer[py * self.screen_w + sx] = darken_fx(color, wall_bright_fx);
+            }
+
+            // ---- floor below the wall --------------------------------------
+            let floor_start = draw_end + 1;
+            if floor_start < self.screen_h {
+                for py in floor_start..self.screen_h {
+                    let floor_dist = self.floor_dist_lut[py];
+
+                    if floor_dist > 15.0 {
+                        // Far floor → just a dark pixel, skip texture & world calc.
+                        let gray = darken_fx(0xFF80_8080, self.floor_bright_lut[py]);
+                        buffer[py * self.screen_w + sx] = gray;
+                    } else {
+                        let fx = game.player.x + floor_dist * rdx;
+                        let fy = game.player.y + floor_dist * rdy;
+
+                        let ftx = ((fx.fract().abs() * TEX_SIZE as f64) as usize).min(TEX_SIZE - 1);
+                        let fty = ((fy.fract().abs() * TEX_SIZE as f64) as usize).min(TEX_SIZE - 1);
+
+                        let color = game.floor_texture[fty * TEX_SIZE + ftx];
+                        buffer[py * self.screen_w + sx] =
+                            darken_fx(color, self.floor_bright_lut[py]);
+                    }
+                }
+            }
+        }
+
+        // ---- crosshair -----------------------------------------------------
+        let cx = self.screen_w / 2;
+        let cy = self.screen_h / 2;
+        let cross_color = 0xFF00_FF00;
+        for i in 0..=4isize {
+            if cy as isize - i >= 0 {
+                buffer[(cy - i as usize) * self.screen_w + cx] = cross_color;
+            }
+            if (cy + i as usize) < self.screen_h {
+                buffer[(cy + i as usize) * self.screen_w + cx] = cross_color;
+            }
+            if cx as isize - i >= 0 {
+                buffer[cy * self.screen_w + (cx - i as usize)] = cross_color;
+            }
+            if (cx + i as usize) < self.screen_w {
+                buffer[cy * self.screen_w + (cx + i as usize)] = cross_color;
+            }
+        }
+    }
+}
+
+/// Integer darken: `bright_fx` is brightness × 256 in fixed-point.
+#[inline(always)]
+fn darken_fx(color: u32, bright_fx: u32) -> u32 {
+    let r = (((color >> 16) & 0xFF) * bright_fx) >> 8;
+    let g = (((color >> 8) & 0xFF) * bright_fx) >> 8;
+    let b = ((color & 0xFF) * bright_fx) >> 8;
+    0xFF00_0000 | (r << 16) | (g << 8) | b
+}